Coating-Enabled Buffer-Gas-Free Vapor Cell: A New Sensor Architecture for Single-Beam SERF Magnetometers

Alkali metal vapor cells are fundamental components in quantum sensors, and their relaxation characteristics critically influence both sensitivity and system stability. In Spin-Exchange Relaxation-Free (SERF) atomic magnetometers, although spin-exchange collisions are effectively suppressed, wall-collision-induced relaxation remains the primary limiting factor. A coating-enabled buffer-gas-free vapor cell (CBF-VC) is proposed as a novel sensor unit, realized through multilayer octadecyltrichlorosilane (OTS) selfassembled molecular coatings. The CBF-VC is integrated into a single-beam SERF atomic magnetometer, and experimental validation is conducted. The results indicate a significant extension of the wall collision relaxation time from 40.19 ms. This extended relaxation time directly enhances the magnetometer sensitivity by 48%, confirming the feasibility of CBF-VCs as a measurement-oriented vapor cell architecture. The findings demonstrate not only the effectiveness of anti-relaxation coatings, but also a new instrumentation pathway for advancing next-generation quantum sensing.